.bam stands for buffered attenuator multiple. its actually a bipolar attenuator with a gain ratio of 2:1 which cascades into a 1 in / 4 out buffered multiple. when the multiple input jack is used, the normalled
connection from the bipolar attenuator to the buffered multiple is broken, therefore you can use each section independently or together. this module is 4 hp in size and uses very little power.